Minimally invasive retractor and methods of use

ABSTRACT

A device, system and method for orthopedic spine surgery using a novel screw-based retractor, disclosed herein, that allows for access to the spine through a minimally or less invasive approach. The retractor device is designed to be coupled to a pedicle screw and then to have opposed arms of the retractor spread apart to open the wound proximally. The retractor is removed by pulling it out of the wound whereby the retractor is deformed to pass over the pedicle screw head. The retractor is intended to be made of a stiff plastic material, sterile packaged and disposable after one use. A system and method for using the retractor and performing a minimally invasive spine surgical procedure are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. application Ser. No.13/648,409, filed on Oct. 10, 2012, which is a continuation of U.S.application Ser. No. 12/941,143, filed on Nov. 8, 2010, now U.S. Pat.No. 8,298,138, which is a divisional of U.S. patent application Ser. No.11/528,223, filed on Sep. 26, 2006, now U.S. Pat. No. 7,846,093, whichclaims priority to U.S. Provisional Application Ser. No. 60/720,670,filed on Sep. 26, 2005, the entire contents of each of which areincorporated herein by reference.

BACKGROUND

1. Field of the Invention

This invention relates generally to orthopaedic spine surgery and inparticular to a minimally invasive retractor and methods for use in aminimally invasive surgical procedure.

2. Background of the Technology

There has been considerable development of retractors and retractorsystems that are adapted for use in less invasive procedures. Many ofthe recent developments are based on traditional types of surgicalretractors for open procedures, predominantly table-mounted devices ofvarious designs. These devices tend to be cumbersome and are not welladapted for use in small incisions. Standard hand-held surgicalretractors are well known in the prior art and can be modified to fitthe contours of these small incisions, but they require manualmanipulation to maintain a desired placement, thereby occupying one handof the physician or requiring another person to assist the physicianduring the procedure. Typical retractors are also positioned into thesoft tissue and are levered back to hold the wound open, frequentlyrequiring re-positioning if they dislodge, obstruct the physician'sview, or interfere with access to the surgical site.

In recent years, minimally invasive surgical approaches have beenapplied to orthopaedic surgery and more recently to spine surgery, suchas instrumented fusions involving one or more vertebral bodies. Unlikeminimally invasive procedures such as arthroscopic knee surgery orgallbladder surgery where the affected area is contained within a smallregion of the body, spinal fusion surgery typically encompasses aconsiderably larger region of the patient's body. In addition,arthroscopic surgery and laparoscopic surgery permit the introduction offluid (i.e. liquid or gas) for distending tissue and creating workingspace for the surgeon. Surgery on the spine does not involve a capsuleor space that can be so distended, instead involving multiple layers ofsoft tissue, bone, ligaments, and nerves. For these reasons, the idea ofperforming a minimally invasive procedure on the spine has only recentlybeen approached.

By way of example, in a typical spine fusion at least two vertebralbodies are rigidly connected using screws implanted into the respectivevertebral bodies with a solid metal rod spanning the distance betweenthe screws. This procedure is not generally conducive to a minimallyinvasive approach. The insertion of pedicle or facet screws isrelatively straightforward and can be accomplished through a minimalincision. The difficulty arises upon the introduction of a length of rodinto a very small incision with extremely limited access and visibility.A single level fusion may require a 30-40 mm rod to be introduced into a1 cm incision and a multilevel fusion may require a rod several incheslong to fit into a 1 cm incision. For this reason, it is important thatthe minimal incision be maintained in an open and accessible condition(i.e. as wide as practicable) for introduction of the rod.

Minimally invasive surgery offers significant advantages overconventional open surgery. First, the skin incision and subsequent scarare significantly smaller. By using more than one small incision ratherthan one large incision, the need for extensive tissue and muscleretraction may be greatly reduced. This leads to significantly reducedpost-operative pain, a shorter hospital stay, and a faster overallrecovery.

Most spine implant procedures are open procedures, and while manymanufacturers advertise a minimally invasive method, the procedure istypically not recommended for fusions and focuses on more common andaccepted minimally invasive spine procedures such as kyphoplasty,vertebroplasty, and discectomy.

Medtronic Sofamor Danek's SEXTANT® is a true minimally invasive deviceused for screw and rod insertion. Its shortcomings lie with howcomplicated the system is to use and the requirement for an additionalincision for rod introduction. This system also requires that theguidance devices be rigidly fixed to the pedicle screw head in order tomaintain instrument alignment and to prevent cross-threading of thesetscrew. For these reasons, the surgeon cannot access the surroundinganatomy for complete preparation of the field. Nor does SEXTANT® allowfor any variation in the procedure, if need be.

Depuy Spine's VIPER™ system is another minimally invasive implant andtechnique recommended for one or two level spine fusions. This system isless complicated than the SEXTANT® only requiring two incisions for aunilateral, one-level fusion, but it is limited in the same way as theSEXTANT® because it also requires the instrumentation to be rigidlyfixed to the pedicle screw.

Spinal Concept's PATHFINDER® and NuVasive's SPHERX® spinal system (asdisclosed in U.S. Pat. No. 6,802,844), are marketed as “minimallydisruptive” spine fusion implants and procedures. While they haveadvantages over a general “open” procedure, they do not provide all ofthe advantages of a truly minimally invasive approach. Theircharacterization as “minimally open” procedures is a result of theinherent difficulty of introducing a rod in a minimally invasive spinalprocedure. In order to introduce a rod long enough to accomplish asingle level fusion, these systems describe an incision long enough toaccept such a rod, thereby undermining the advantages of a minimallyinvasive approach.

The problem of rod introduction warrants further discussion as it is thecentral problem in minimally invasive spinal fusions. The systemscurrently on the market address this issue by adding another incision,using a larger incision, or avoiding the issue completely for fusionsgreater than one level.

In order to be truly minimally invasive, a spine fusion procedure shouldhave a minimum number of small incisions and not require significanttissue and/or muscle retraction. Furthermore, an improved approachshould encompass as many variations and applications as possible therebyallowing the surgeon to adjust the procedure to accommodate the anatomyand surgical needs of the patient as presented. For instance, spinalfusions should not be limited to just one or two levels.

Therefore, a continuing need exists for an improved device, an improvedsystem, and an improved method for performing minimally invasive spinesurgery.

SUMMARY

The present disclosure relates to a device, a system, and a method for ascrew-based retractor used in performing minimally invasive spinesurgery. The retractor is removably attached to a pedicle bone screwthat is used to guide the retractor into place and act as a point offixation with respect to the patient. Multiple retractors may be used inconjunction with a single screw to allow retraction in multipledirections and multiple retractors may be used with multiple screws,respectively, during a single spine procedure. The retractor may bemanufactured for a single use or can be sterilized and reused. Finally,the retractor may also act as a guide that will aid in the insertion ofinstruments and implants.

In its nominal position, the retractor will form a generally cylindricaltube with at least one retracting blade. Instrument holes are locatedperpendicular to the long axis of each retracting blade whereby astandard surgical instrument, such as a Gelpi Retractor, can be used toseparate the blades to retract the skin and soft tissue and maintain thefield of view. Yet, where the retractor is connected to the pediclescrew the retractor maintains a circular cross-section. Since theretractor is not permanently fixed but is removably attached to thepedicle screw, it is free to have polyaxial rotation allowing thesurgeon greater wound access and freedom to operate. Furthermore,polyaxial rotation allows the retractor to expand medial-laterally aswell as cephalad-caudally and any combination thereof. This freedom ofmovement proximally and non-rigid attachment distally decreases the needfor retractor re-positioning during a procedure. Proximal stabilizationof the retractor is possible when it is used in conjunction with atable-mounted retractor.

The minimally invasive retractor can be designed to flex proximal ordistal to the pedicle screw head. In one embodiment, the retractor has a“living hinge” incorporated into the retractor's blade design. More thanone living hinge can be incorporated to aid in bending along any portionof the blade's length.

The cross-section of the blade is a circular ring sector to provideadditional stiffness. The geometry will force the blade to bend at theliving hinge and still be able to retract the soft tissue pressedagainst it.

Minimally invasive retractors having a living hinge or a true hingelocated may include at least one window that is aligned with the pediclescrew saddle and allows the insertion of instruments into the surgicalsite.

The distal tip of the minimally invasive retractor is bullet shaped toaid in insertion through the soft tissue to where it will seat againstthe pedicle. The distal tip will also have one or more relief featurescut into it to aid in removing the retractor. Upon completion of theprocedure, the retractor can be pulled straight out of the wound and thedistal tip will expand or separate to pass over the screw and rodassembly. Advantageously, by positioning the distal tip of the retractoraround the head of the screw adjacent the bone, the retractor retractssoft tissue from a point below the head of the screw, creating excellentvisibility of the screw and surrounding tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the presently disclosed minimally invasive retractor aredescribed herein with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of a minimally invasive retractor accordingto a first embodiment of the present disclosure;

FIG. 2 is a bottom view of the minimally invasive retractor of FIG. 1;

FIG. 3 is a perspective view of a minimally invasive retractor accordingto a second embodiment of the present disclosure;

FIG. 4 is a bottom view of the minimally invasive retractor of FIG. 2;

FIG. 5 is a side view of a minimally invasive retractor and screwassembly including the minimally invasive retractor of FIG. 1;

FIG. 6 is a perspective view of the minimally invasive retractor andscrew assembly of FIG. 5;

FIG. 7 is an enlarged side view of the detailed area “A” of FIG. 5;

FIG. 8 is a perspective view of a minimally invasive retractor and screwassembly according to a third embodiment of the present disclosure;

FIG. 9 is a top view of the minimally invasive retractor and screwassembly of FIG. 8 showing a rod extending through an expanded passageof the minimally invasive retractor;

FIG. 10 is a perspective view of a fourth embodiment of the presentlydisclosed minimally invasive retractor;

FIG. 11 is a perspective view of a fifth embodiment of the presentlydisclosed minimally invasive retractor;

FIG. 12 is a perspective view of a sixth embodiment of the presentlydisclosed minimally invasive retractor;

FIG. 13 is a top plan view of bone biopsy needle;

FIG. 14A is a perspective view of a scalpel;

FIG. 14B is a side view of a dilator and retractor;

FIG. 15A is a side view of a cannulated bone screw tap;

FIG. 15B is a front elevational view of the bone screw tap of FIG. 15;

FIG. 15C is an enlarged side view of the detailed area “A” of FIG. 15;

FIG. 16 is a perspective view of a screw inserter having ananti-rotation sleeve;

FIG. 17 is an exploded side view of the screw inserter of FIG. 16 shownwith a spine screw;

FIG. 18 is a side view of a screw insertion assembly including the screwinserter of FIG. 16, a minimally invasive retractor with a spine screw;

FIG. 19 is a perspective view of a retraction assembly having aminimally invasive retractor and a Gelpi retractor;

FIG. 20A is a perspective view of a cannulated screw showing a rodpositioned in a rod receiving passage;

FIG. 20B is top view of the screw of FIG. 20;

FIG. 20C is a perspective view of the screw of FIG. 20 illustrating anoptional guidewire inserted therethrough;

FIG. 21 is a perspective view of a retractor extractor instrumentaccording to an embodiment of the present disclosure;

FIG. 22 is an exploded perspective view of the retractor extractorinstrument of FIG. 18;

FIG. 23 is a perspective view of the retractor extractor instrument ofFIG. 21 coupled to a minimally invasive retractor which is associatedwith a spine screw;

FIG. 24 is a front cross-sectional view of a vertebral body with a pairof minimally invasive retractors attached using screws with the bladesin their initial position and rods positioned in the passages of theminimally invasive retractors;

FIG. 25 is a front cross-sectional view of the vertebral body with apair of minimally invasive retractors attached using screws afterretracting tissue with rods positioned in the passages of the minimallyinvasive retractors;

FIG. 26 is a front cross-sectional view of a body illustrating insertionof the bone biopsy needle of FIG. 13 into a vertebral body;

FIG. 27 is a front cross-sectional view of the body of FIG. 26illustrating insertion of a guide wire through the bone biopsy needle;

FIG. 28 is a front cross-sectional view of the body of FIG. 27illustrating tissue separation using the scalpel of FIG. 14;

FIG. 29 is a front cross-sectional view of the body of FIG. 27illustrating insertion of the screw insertion assembly of FIG. 18; and

FIG. 30 is a front cross-sectional view of the body of FIG. 29 with thevertebral body shown in a cross-sectional view and illustratingattachment of the screw of the screw insertion assembly to the vertebralbody.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the presently disclosed minimally invasive retractiondevice will now be described in detail with reference to the drawingswherein like reference numerals identify similar or identical elements.In the drawings and in the description which follows, the term“proximal”, as is traditional, will refer to the end of the minimallyinvasive retraction device which is closest to the operator while theterm “distal” will refer to the end of the device which is furthest fromthe operator.

Referring initially to FIGS. 1 and 2, a first embodiment of thepresently disclosed minimally invasive retractor or retractor isillustrated and generally designated as 10. Retractor 10 includes anopen proximal end 12 and a distal end 14. In addition, retractor 10includes a pair of retractor blades 8 having a plurality of instrumentholes 6 disposed on each of retractor blades 8. Instrument holes 6 areconfigured and dimensioned to cooperate with different surgicalinstruments as will be discussed in detail hereinafter. A distal region9 of retractor 10 includes an opening 7 (FIG. 2), at least one slot orwindow 2, and a pair of arms 13 extending from distal end 14 to aflexible region or living hinge 4. Window 2 is sized and configured toreceive instruments therethrough. Each retractor blade 8 is attached toliving hinge 4 to define a substantially continuous elongate member. Apair of recesses 4 a are formed between retractor blade 8 and arm 13 todefine living hinge 4.

Distal end 14 further includes at least one relief region R (FIG. 2)defined by at least one slit 16 extending proximally from opening 7(FIG. 2). Alternatively, slit 16 may originate at window 2 and extenddistally towards opening 7. It is contemplated that other arrangementsof relief structures may be used to define relief region R and these mayexist between opening 7 and window 2. Each slit 16 is a weakened portionof distal end 14. It may be a score in the material, a perforated regionin the material, or another structural arrangement allowing reliefregion R to be radially displaced away from the centerline of retractor10 in response to applied forces as will be discussed in detailhereinafter. In addition, distal end 14 has a generally convex outersurface that facilitates insertion of retractor 10 through layers ofbody tissue.

Refractor blades 8 and arms 13 are generally arcuate structures thatcooperate to define a substantially circular configuration for retractor10. Each retractor blade 8 and each arm 13 have an arcuate configurationthat is less than about 180° and are radially spaced apart to define acontinuous slot 17 along a substantial portion of retractor 10. Inaddition, each retractor blade 8 and its corresponding arm 13 define apassage 18 that also extends substantially the entire length ofretractor 10. Passage 18 is expandable, as will be discussed in detailhereinafter, for receiving a rod 3 (FIG. 9) therein. Retractor blades 8and arms 13 define a substantially circular ring shape, therebyproviding sufficient stiffness (i.e. rigidity) such that retractorblades 8 and arms 13 resist bending from the counter forces of theretracted tissues.

Opening 7 is located at distal end 14 of retractor 10 and is sized forreceiving the shank of a threaded screw 40 (FIG. 20) therethrough, butinhibiting passage of a head 42 of screw 40 so as to support screw 40 atdistal end 14 of retractor 10. The interior surface of distal end 14 hasa generally concave spherical geometry that is adapted to mate with head42 of pedicle screw 40 that is best seen in FIG. 11.

Retractor 10 is formed from a suitable biocompatible material having thedesired physical properties. That is, retractor 10 is formed of abiocompatible, sterilizable material in a suitable configuration andthickness so as to be sufficiently rigid to be held on the screw whendesired during insertion and a surgical procedure and to provideretraction of tissue, and yet is sufficiently bendable to be spreadapart to provide retraction and to be forcibly removed from the screw asnecessary and appropriate. It is contemplated that retractor 10 may beformed from polymers such as polypropylene, polyethylene, orpolycarbonate. Additionally, retractor 10 may be formed from silicone,polyetheretherketone (“PEEK”), or another suitable material. Retractorblade 8 is bendable away from the centerline of retractor 10 in responseto applied forces, wherein retractor blade 8 bends at living hinge 4.Bending retractor blade 8 away from the centerline (i.e. radiallyoutwards) creates a larger opening through retractor 10 and also acts toretract the surrounding tissue at the selected surgical site.Installation and use of retractor 10 in surgical procedures will bediscussed in detail hereinafter.

Referring now to FIGS. 3 and 4, a second embodiment of the presentdisclosure is illustrated as retractor 30 having an open proximal end 32and a distal end 34. Retractor 30 includes a pair of retractor blades36. Similar to retractor 10, distal end 34 has an interior surface witha generally concave spherical geometry that is adapted to mate with thehead of a pedicle screw and has a generally convex outer surface thatfacilitates insertion of retractor 30 through layers of body tissue.Additionally, retractor 30 includes an opening 7 (FIG. 4) that issubstantially identical to opening 7 of retractor 10.

As in the previous embodiment, blades 36 have an arcuate configurationthat is less than about 180° and are radially spaced apart to define acontinuous slot 37 along a substantial portion of retractor 30.Additionally, retractor blades 36 define a passage 35 through retractor30. In this embodiment, retractor blades 36 are also flexible, but bendradially outwards from a centerline of retractor 30 near relief regionsR (FIG. 4). As in the previous embodiment, relief regions R are definedby slits 16 (shown as a pair of slits in FIG. 4) as previously discussedin connection with retractor 10. In this embodiment, retraction oftissue with retractor blades 36 utilizes manual manipulation ofretractor blades 36 by the physician rather than using a surgicalinstrument in cooperation with instrument holes 6 of retractor 10 (FIG.1). Removal of retractor 30 from the surgical site is accomplished bypulling retractor 30 proximally (i.e. away from the pedicle screw) andspreading or breaking distal end 34 along slits 16 such that reliefregions R and retractor blades 36 separate from each other. As such, thephysician can readily remove the two parts from the surgical site.Similar to passage 18 (FIG. 1), passage 36 is selectively expandable andcontractible for receiving rod 3 therein.

In FIGS. 5-7, retractor 10 is illustrated in an assembled condition witha pedicle screw 40. Pedicle screw 40 extends through opening 7 (FIG. 7)such that threads of pedicle screw 40 extend beyond distal end 14 (FIG.7) for insertion into a target site in a bone (e.g. a vertebral body).As shown in the figures, when pedicle screw 40 is inserted in retractor10, the head of pedicle screw 42 (FIG. 20) mates with the interiorgeometry of distal end 14. As shown, rod receiving passage 44 of pediclescrew 40 (FIG. 20) aligns with opening 17 between retractor blades 8facilitating the insertion of rod 3 (FIG. 20) into screw head 42. Inaddition, pedicle screw 40 is pivotable about the longitudinal axis ofretractor 10 allowing retractor 10 to be attached in a first angularorientation with respect to the vertebral body, but pivotable aboutpedicle screw 40 increasing the amount of tissue that may be retractedusing retractor 10.

Another embodiment of the presently disclosed retractor is illustratedin FIGS. 8 and 9 and shown generally as retractor 50. Retractor 50 issimilar to retractor 10, but includes a plurality of living hinges 4along with their corresponding recesses 4 a. Retractor 50 is about 6inches long and is readily adjusted to a desired length by removingexcess material using scissors or a knife. In addition, retractor 50 hasan inner diameter that is approximately 16 mm and retractor blades areapproximately 1 mm thick. Each living hinge 4 is about 1-2 mm in heightand each blade section 8 a is about 5 mm. Instrument holes 6 are on 1 cmcenterlines. Slot 17 is typically at least 5.5 mm, but will varyaccording to the size of the rod that will be inserted into the patient.In particular, each refractor blade 8′ includes a plurality of bladesections 8 a. Each blade section 8 a is connected to an adjacent bladesection 8 a by a living hinge 4. Thus, the plurality of blade sections 8a and living hinges 4 define retractor blade 8′. As in the previousembodiment (FIG. 1), each blade section 8′ is substantially parallel toarm 13 to define slot 17 between refractor blades 8′.

When retractor blades 8′ are urged radially outward from their initialor rest position towards their retracted position, the size of passage18 increases. This increase in the size and area of passage 18 improvesaccess to the surgical target site (i.e. near where the retractor isinserted into tissue), thereby increasing visibility of the target site,access for instruments, and access for surgical implants. As shown inFIG. 9, rod 3 is positioned in passage 18 after the surrounding tissuehas been retracted using retractor 50. These advantages will bediscussed in detail hereinafter. Additionally, the plurality of livinghinges 4 greatly increases the adaptability of retractor 50 incomparison to retractor 10. While refractor blades 8 of retractor 10(FIG. 1) generally bend at its single living hinge 4, the additionalliving hinges 4 present along retractor blades 8′ of retractor 50 permitbending with increased flexibility at a number of positions along thelength of each retractor blade 8′. Thus, retractor blades 8′ will bendat the living hinge 4 that corresponds to the plane defined by thesurface of the patient's body tissue. By using this construction,retractor 50 is usable in patient's having different tissue thicknessesbetween the vertebral body and the surface of their skin. In addition,since each retractor blade 8′ has a plurality of living hinges 4 andblade sections 8 a, it is not required for each retractor blade 8′ tobend at the same point along the length of retractor 50, therebyaccommodating variances in the depth that retractor 50 is inserted. Forexample, one retractor blade 8′ may bend at its fourth living hinge 4,while the other retractor blade 8′ may bend at its sixth living hinge 4,thereby accommodating variances in tissue thickness and orientation ofretractor 50.

In FIG. 10, a further embodiment of the presently disclosed retractor isillustrated and generally referenced as retractor 60. Retractor 60 issimilar to retractor 10 (FIG. 1) with the differences discussed indetail hereinafter. As in the previous embodiment, retractor 60 includesa distal end 14 a with a distal region 9 a. Distal region 9 a includesarms 13 a that extend circumferentially and do not form a portion ofslot 17 as in the previous embodiment. A living hinge 4′ is definedbetween window 2 and slot 17. In addition, distal region 9 a includesslits 16 a that are full cuts through the material of distal region 9 adefining a plurality of relief regions R′. In this embodiment, reliefregions R′ are more flexible such that retractor 60 may be separatedfrom a pedicle screw (not shown) and subsequently affixed to the pediclescrew. This configuration permits a surgeon to remove and subcutaneouslyrelocate retractor 60 to gain access to the vertebral disc space. As inthe previous embodiments, positioning window 2 distally of slot 17allows retractor 60 to expand in a medial-lateral orientation such thatrod 3 (FIG. 8) may be inserted through passage 18 into the target site.

FIG. 11 illustrates an alternate embodiment of the presently disclosedretractor that is generally referenced as 70. Retractor 70 issubstantially similar to the embodiment previously identified asretractor 60 (FIG. 10). However, in this embodiment distal region 9 bonly includes one arm 13 a, thereby increasing the lateral opening neardistal end 14 b and defining window 2 a that is larger than previouslydisclosed window 2 (FIG. 10). This embodiment provides increased accessto the target site, thereby allowing larger implants or instruments tobe positioned in the target site.

Another embodiment of the presently disclosed retractor is illustratedin FIG. 12 and referenced as retractor 80. Retractor 80 includes thesame or substantially similar components as described hereinabove withrespect to retractor 10 (FIG. 1). In this embodiment, retractor 80includes only one retractor blade 8. This configuration allows greatervariability in creating the retracted space as well as increasing accessto the target site for using larger instruments or inserting largerdevices than possible with retractor 10 (FIG. 1).

It is contemplated that any of the previously disclosed retractors maybe formed of a bendable resilient material such that when externalspreading forces (i.e. from a Gelpi retractor or the physician's hands)are removed, the retractor blades will return towards their initialposition (e.g., substantially parallel to the centerline). It is alsocontemplated that any of the previously disclosed retractors may beformed of a bendable non-resilient material such that when the externalspreading forces are removed, the retractor blades resist returning totheir initial position and remain in the retracted position.

Other components of the presently disclosed system will now be discussedwith reference to FIGS. 13-23. In FIG. 13, a bone biopsy needle (e.g. aJamshidi needle) 100 is illustrated. Needle 100 includes a handle 102disposed at a proximal end of needle 100, an elongate tubular member 104extending distally from handle 102, and a stylet 106. Stylet 106 has asharpened distal tip 108 that is adapted for penetrating tissue,including bone. In addition, tubular member 104 has a lumen extendingfrom its proximal end to its distal end for receiving stylet 106therethrough. Stylet 106 is releasably attached to handle 102 such thatit may removed once the target site has been pierced by distal tip 108.After stylet 106 is removed, a guidewire 1 (FIG. 27) may be insertedthrough tubular member 104 and secured or attached at the target siteusing known techniques.

Referring now to FIG. 14, a cannulated scalpel 120 is illustrated.Scalpel 120 includes a housing 125 having a blade 126 disposed therein.Blade 126 has a sharpened distal end 124 for separating tissue. Inaddition, distal end 124 includes an opening 124 a that cooperates withan opening 128 located at proximal end 122 and defines a channel throughscalpel 120 for slidably receiving guidewire 1 (FIG. 14A) therethrough.

FIG. 14A shows a dilator 300 configured and dimensioned to be receivedthrough a retractor 10 with distal atraumatic blunt tip 302 protrudingthrough opening 7 in retractor 10. Dilator 300 includes a longitudinalpassage therethrough having a distal opening 304 for receiving guidewire1 therethrough. Alternatively, it is contemplated that rather than aretractor, dilator 300 may be used together with a cannula (not shown).Although less desirable, a series of dilators and cannulas can be used.

In FIGS. 15-15B, a cannulated bone tap 140 is shown. Bone tap 140includes an elongated body 142 having a proximal end 146 and a distalend 144. Distal end 144 includes a helical thread 145 for formingthreads in a hole that is formed in a bony structure (i.e. a vertebralbody). Proximal end 146 includes a tool engagement region 147 that isadapted for cooperating with a driving or rotating tool 178 (FIG. 29)and forming the threads in the bony structure. Driving and rotatingtools are well known in the art. In addition, proximal end 146 anddistal end 144 cooperate to define a channel 148 extending through bonetap 140 such that bone tap 140 may be slid along guidewire 1. Bone tap140 is available in a number of different sizes in a range of about 5.5mm to about 7.5 mm. Alternatively, other bone taps may be used thatmatch the size of the screw threads of the screw that will be implantedinto bone.

A screw inserter 160 is illustrated in FIGS. 16 and 17. Screw inserter160 includes an anti-rotation sleeve 150 and a housing 170. Housing 170includes a body 172 having a pair of handles 174 extending therefrom.Handles 174 facilitate positioning and/or rotating screw inserter 160. Atubular member 176 extends distally from body 172 and includes aplurality of holes 175. A shaft 166 (FIG. 17) is disposed through alumen of tubular member 176 and is rotatable therein. A tool engagingsurface 163 is disposed at a proximal end 162 of shaft 166. At a distalend 164 of shaft 166, a screw engaging structure 165 is disposed that isadapted and configured to releasbly engage a head 42 of pedicle screw40. In particular, screw inserter includes a cross-member 164 andthreads 173. During assembly of screw inserter 160 and pedicle screw 40(FIG. 20), screw engaging structure 165 is inserted into head 42 suchthat cross-member 163 occupies rod receiving recess 44 and threads 173engage threaded portion 45 of pedicle screw 40. This arrangementreleasably secures pedicle screw 40 to screw inserter 160. Whenassembled with pedicle screw 40, rotation of shaft 166 also causesrotation of pedicle screw 40 without causing rotation of housing 170.Anti-rotation sleeve 150 is located along an outer surface of tubularmember 176 and includes protruding pins or buttons 152.

As best seen in FIG. 18, buttons 152 are configured and adapted toreleasably engage instrument holes 6 of retractor 10. Although retractor10 is illustrated in cooperation with screw inserter 160, screw inserter160 is configured and adapted to cooperate with retractor 50, 60, and70. Buttons 152 of screw inserter 160 engage instrument holes 6 suchthat no rotational forces are transferred to the selected retractorwhile rotating and inserting pedicle screw 40 into a selected vertebralbody. This arrangement permits insertion of pedicle screw 40 whileminimizing displacement of the selected retractor from its desiredlocation (i.e. target site).

A common spreader, or Gelpi retractor 180 is shown in FIG. 19 incooperation with retractor 10. Gelpi retractor 180 includes a pair ofcurvate arms 185 that are pivotably connected at pivot point 186. A pairof finger rings 184 are located at a proximal end of Gelpi retractor 180that permit the physician to selectively move arms 185 towards and awayfrom each other. A finger 182 is located at a distal end of each arm 185and is configured to releasably engage an instrument hole 6 in retractor10. As shown, finger rings 184 are laterally offset from arms 185. Thus,pivotable movement of arms 185 urge retractor blades 8 towards and awayfrom each other in response to movement of finger rings 184. Movingfinger rings 184 towards each other pivots arms 185 away from each otherand urge retractor blades 8 away from each other, thereby enlargingpassage 18. Consequently, movement of finger rings 184 away from eachother has the opposite effect. Gelpi retractor 180 is also configuredand adapted to cooperate with retractor 50, 60, and 70.

FIGS. 20-20B illustrate a cannulated minimally invasive pedicle screw40. Pedicle screw 40 includes a helical thread 43 that is sized andconfigured for insertion into a threaded hole created by bone tap 140. Ahead 42 includes a tool engaging portion that is adapted to cooperatewith screw insterter 160 as previously discussed. A rod receivingpassage 44 is formed in head 42. In addition, head 42 includes athreaded portion 45 that is adapted to removably attach to the screwinserter 160 and receive a setscrew (not shown). The setscrew compressesagainst rod 3 in passage 44 and frictionally engages rod 3 to hold it ina desired position. Setscrews are well known in the art. A throughbore47 extends between a proximal end and a distal end of pedicle screw 40for receiving guidewire 1 therethrough (FIG. 20B).

A retractor extractor instrument 200 is illustrated in FIGS. 21-23.Retractor extractor 200 includes handle portion 190, arms 210 and 220,and extractor bar 230. Handle portion 190 includes a handle grip 192having openings 193, 194 disposed at one end thereof. Pin 196 extendsthrough opening 194 and pivotably couples handle portion 190 to arms210, 220 by extending through holes 212, 222 of arms 210, 220. A pin 195extends through opening 193 and pivotably couples handle portion 190 topivot bar 198 through hole 198 a. At an opposing end of pivot bar 198,hole 198 b receives a pin 197. Pin 197 extends between arms 210, 220 andis slidably captured therebetween. In particular, pin 197 slidesproximally and distally within a recess 224 of arm 220. Arm 210 has anidentical recess that is not shown. Additionally, pin 197 extendsthrough an opening 236 of extractor bar 230. Retractor bar has a slot230 that extends parallel to its longitudinal axis and slidably receivesposts 202 therethrough. Posts 202 are attached to blade portions 216,226 through openings 218, 228. Additionally, posts 202 are adapted toreleasably engage instrument holes 6 of the previously disclosedretractors (FIG. 23). At a distal end of extractor bar 230, a blunt end234 is located for bluntly engaging head 42 of pedicle screw 40 or a roddisposed therein.

Pivoting handle grip 192 towards arms 210, 220 simulataneously movesextractor bar 230 distally (i.e. towards the screw) such that pins 202on arms 210, 220 and distal blunt end 234 move apart relative to eachother. This simultaneous relative movement between extractor bar 230 andpins 202 causes the retractor to separate from the pedicle screw at therelief regions without applying any appreciable downward forces on theimplant or the patient.

Use of the presently disclosed system will now be described withreference to FIGS. 24-30. In a first method, retractor 10 is assembledwith pedicle screw 40 as shown in FIG. 24. The assembled apparatus isinserted into an incision through the patient's skin S and muscle/fattissue T such that pedicle screw 40 is subsequently threaded into avertebral body V. Once the desired number of retractors 10 are affixedto vertebral body V, retractor blades 8 are spread apart to retract skinS and tissue T to create a retracted area at the target site.Alternatively, retractor 50 may be assembled with pedicle screw 40 toretract tissue as shown in FIG. 25. In either method, rod 3 is insertedin passage 18 when passage 18 is in an expanded state (i.e. tissue hasbeen retracted). Additionally, rod 3 is repositioned through passage 18and subcutaneously such that is may be secured to fastening regions ofpedicle screws in adjacent vertebral bodies.

Turning now to FIGS. 26-30, an alternate technique is illustrated.Biopsy needle 100 is inserted through skin S of the patient until itsdistal end contacts the selected point on vertebral body V. Biopsyneedle 100 may be inserted in a known manner, such as percutaneouslyunder fluoroscopic imaging, or under optical or magnetic image guidance(such as the STEALTH® system available from Medtronic Sofamor Danek). Asmall puncture in the vertebral body V is made using sharpened distaltip 108 (FIG. 13). After pin 106 is removed from biopsy needle 100,guidewire 1 is inserted through biopsy needle 100 and affixed tovertebral body V. Guidewire 1 now is in position to direct furtherinstruments and devices to the selected location on vertebral body V.Alternately, guidewire 1 may be inserted into vertebral body V withoutfirst using biopsy needle 100. The size of the working area may beincreased at the physician's discretion. In instances where it isdesired to increase the working area, the physician may use scalpel 120along guidewire 1 (FIG. 28) to dissect additional tissue. In order topermit inspection of the position of guidewire 1 prior to insertion of aspine screw, a dilator 300 and optional retractor 10 may be insertedover the guidewire by inserting guidewire 1 through dilator opening 304(FIG. 14A) with the dilator inserted through retractor 10. Once thedilator tip with retractor is inserted to the target site, the dilatormay be removed and placement of the guidewire may be inspected throughthe retractor. If the surgeon is satisfied with the placement ofguidewire 1, then the procedure may continue through the retractor orthe retractor may be removed and another inserted with a screw. If, onthe other hand, the surgeon desires to change the guidewire location,another guidewire may be placed through the retractor, such as byinserting bone biopsy needle 100 through the retractor to a differentplacement in the bone and inserting a new guidewire at the new location.The former guidewire may then be removed. If desired, the physician maypre-drill a threaded bore in vertebral body V using bone tap 140inserted along guidewire 1 to prepare the bore.

Once the target site is ready to accept a pedicle screw and retractor,an assemby including pedicle screw 40, retractor 10, and screw inserter160 is slid along guidewire 1 to reach the target site. Using optionaldriving handle 178 (FIG. 29), the physician rotates screw inserter 160to drive pedicle screw 40 into vertebral body V (FIG. 30). After pediclescrew 40 is secured in vertebral body V, screw inserter 160 is removedand retractor 10 remains in place secured by the screw which has beeninserted into bone. This technique is also adapted for use withretractor 50. The finished result of the attached retractors is the sameas shown in FIGS. 24 and 25.

Refractor blades 8 are spread apart to retract tissue in the workingarea. As previously discussed, retractor blades 8 may be spread apartusing Gelpi retractor 180 (FIG. 19) or by the physician manuallygrasping retractor blades 8 to urge them apart. After the desiredretraction is achieved, rod 3 is inserted through passage 18 ofretractor 10, 50 and is guided through window 2.

It has been found that a rod of sufficient length for a multiple levelimplant construct may be inserted subcutaneously so that the rod isaligned with and inserted into a plurality of screw heads. Thistechnique may be particularly useful in so-called 360 degree procedureswhere an interbody implant is inserted using an anterior approach and ascrew-rod construct is inserted using a posterior approach.Alternatively, the surgeon may selectively make an incision betweenadjacent retractors. The latter approach permits a rod to be insertedthrough the incision to adjacent screws. Once rod 3 is positionedbetween pairs of pedicle screws 40 and, in particularly through therespective rod receiving passages 44, rod 3 is secured in place usingsetscrews as previously discussed.

Once the screw-rod construct is complete, retractors 10, 50 are removedfrom the patient using retractor extractor 200. Retractor extractor 200is positioned atop pedicle screw 40 such that distal end 234 ofextractor bar 230 (FIG. 23) rests flush against the set screw installedin head 42 of pedicle screw 40 or rests upon the rod installed in analternate pedicle screw. The physician repositions retractor blades 8towards arm blades 216, 226 (FIG. 22) of retractor extractor 200 suchthat posts 202 engage instrument holes 6. Once retractor extractor 200is installed, the physician pivots handle grip 192 towards arms 210,220. This pivotable movement drives extractor bar 230 distally againsthead 42 while simultaneously pulling retractor blades 8 proximally suchthat relief regions R (FIG. 1) separate from each other along slits 16.As such, retractor 10, 50 is separated from pedicle screw 40 withoutimparting significant downward or rotational forces against thepatient's body. Retractor 10, 50 may now be removed from the patient andthis process may be repeated for each installed retractor.

In an alternate procedure, the physician first prepares the surgicalsite including positioning a guidewire as discussed hereinabove,optionally using scalpel 120 to prepare an incision, and inserting oneof the previously disclosed retractors without a pedicle screw. Once theselected retractor is positioned in a desired location, the physicianretracts the surrounding tissue as discussed hereinabove. Subsequently,the physician attaches pedicle screw 40 to the vertebral body V usingscrew inserter 160. In this method, the selected retractor is already inposition prior to attaching pedicle screw 40 to vertebral body V. Inparticular, the physician assembles pedicle screw 40 and screw inserter160. Once assembled, the screw insertion assembly is inserted intopassage 18 of the retractor and pedicle screw 40 is rotated such that itbores into vertebral body V and head 42 seats on the interior surface ofthe distal region of the retractor and thus attaches the retractor tovertebral body V. Optionally, the physician may use cannulated bone tap140 to prepare the bore.

In the disclosed embodiments, each retractor is utilized, but notlimited to, a method whereby an initial incision is made in the skin ofapproximately 10-15 mm in length. Surgeon preference will dictate theneed for one or more stages of dilators to aid in expanding the woundbefore introducing one or more retractors in combination with pediclescrews. Normal surgical techniques may be used to close the incision(s).

In the disclosed embodiments, the retractor may be manufactured frommedical grade plastic or metal, thermoplastics, composites of plasticand metal, or biocompatible materials. A plastic part is made from, butnot limited to, polypropylene and polyethylene. Plastic parts may betransparent or opaque and may have radio opaque markers for visibilityduring various imaging techniques. A metallic part utilizes suchmaterials as, but not limited to, aluminum, stainless steel, andtitanium. In addition, the parts may have a reflective or non-reflectivecoating to aid in increasing visibility in the wound and may have anartificial lighting feature.

The disclosed retractors, as with any surgical instrument and implant,must have the ability to be sterilized using known materials andtechniques. Parts may be sterile packed by the manufacturer orsterilized on site by the user. Sterile packed parts may be individuallypacked or packed in any desirable quantity. For example, a sterilepackage may contain one or a plurality of retractors in a sterileenclosure. Alternatively, such a sterile surgical kit may also includeone or a plurality of bone biopsy needles (FIG. 13), guide wires (FIG.20B), sterile cannulated scalpels (FIG. 14), or dilators (FIG. 14A).

It will be understood that various modifications may be made to theembodiments of the presently disclosed retraction system. Therefore, theabove description should not be construed as limiting, but merely asexemplifications of embodiments. Those skilled in the art will envisionother modifications within the scope and spirit of the presentdisclosure.

For example, while the foregoing description has focused on spinesurgery, it is contemplated that the retractors and methods describedherein may find use in other orthopedic surgery applications, such astrauma surgery. Thus, where it is desired to insert a screw or pin intobone in a minimally invasive manner, or otherwise to access a surgicaltarget site over a guidewire, the dilator, scalpel and retractors (orsome of them) of the present disclosure may be used, with or without abone screw.

What is claimed is:
 1. A surgical retractor comprising: an elongatemember bendable radially outwards to retract surrounding tissue; and acoupling region at a distal end of the elongate member, the couplingregion including an opening at a distal end thereof and at least onerelief region configured to permit the surgical retractor to separatefrom a head of a bone screw upon application of a force.
 2. The surgicalretractor according to claim 1, wherein the at least one relief regionis defined by at least one slit extending from the opening.
 3. Thesurgical retractor according to claim 1, wherein the opening has adiameter larger than a diameter of a shank of the bone screw and smallerthan a diameter of the head of the bone screw.
 4. The surgical retractoraccording to claim 1, wherein the elongate member is rotatable relativeto the bone screw when the elongate member is coupled to the bone screw.5. The surgical retractor according to claim 1, further including aplurality of living hinges along a length of the elongate member.
 6. Thesurgical retractor according to claim 1, wherein the coupling regionincludes an interior surface having a generally concave sphericalgeometry that is adapted to mate with the head of the bone screw.
 7. Thesurgical retractor according to claim 1, wherein the coupling regionincludes an outer surface having a generally convex geometry.
 8. Thesurgical retractor according to claim 1, wherein the elongate memberincludes a pair of surgical retractor blades transitionable between afirst state in which the surgical retractor blades are substantiallyparallel to each other and a second state in which the surgicalrefractor blades define a substantially V-shaped configuration.
 9. Thesurgical retractor according to claim 1, wherein the surgical retractordefines a passage that extends substantially along an entire length ofthe surgical retractor.
 10. The surgical retractor according to claim 9,wherein the passage is configured and dimensioned to receive a dilatortherethrough.
 11. The surgical retractor according to claim 1, whereinthe surgical retractor is formed of a resilient material.
 12. Thesurgical retractor according to claim 1, wherein the surgical retractoris formed of a non-resilient material.
 13. The surgical retractoraccording to claim 1, wherein the force is applied away from the head ofthe bone screw.
 14. A surgical retractor comprising: first and secondretracting members; and a coupling region coupled with the first andsecond retracting members, the coupling region disposed at a distal endof the surgical retractor, the coupling region including an openingconfigured to receive a shank of a bone screw and at least one reliefregion configured to permit the surgical retractor to separate from ahead of the bone screw upon application of a force to disengage thesurgical retractor from the head of the bone screw, wherein the firstretracting member is bendable relative to the second retracting member.15. The surgical retractor according to claim 14, wherein the first andsecond retracting members are rotatable relative to the bone screw whenthe surgical retractor is coupled to the bone screw.
 16. The surgicalretractor according to claim 14, wherein the at least one relief regionis defined by at least one slit extending from the opening.
 17. Thesurgical retractor according to claim 14, wherein the coupling regionincludes an interior surface having a generally concave sphericalgeometry that is adapted to mate with the head of the bone screw. 18.The surgical retractor according to claim 14, wherein the couplingregion includes an outer surface having a generally convex geometry. 19.The surgical retractor according to claim 14, wherein the first andsecond retracting members are transitionable between a first state inwhich the first and second retracting members are substantially parallelto each other and a second state in which the first and secondretracting members define a substantially V-shaped configuration. 20.The surgical retractor according to claim 14, wherein the surgicalretractor defines a passage that extends substantially along an entirelength of the surgical retractor.
 21. A method of performing surgerycomprising: percutaneously inserting a guidewire through a patient'sskin into a boney structure; inserting a cannulated bone screw andassociated retractor over the guidewire to a target site; implanting thecannulated bone screw into the boney structure; spreading the retractorfrom a pivot point adjacent the cannulated bone screw to retract softtissue and provide access to the target site; severing a portion of theretractor such that a proximal portion of the retractor remains flushwith an external surface of the skin; performing a surgical procedure atthe target site through the retractor; and removing the retractor fromthe cannulated bone screw.
 22. The method of claim 21, wherein spreadingthe retractor apart includes spreading a pair of elongate members of theretractor apart.
 23. The method of claim 22, wherein spreading the pairof elongate members apart includes spreading the pair of elongatemembers apart using a Gelpi retractor.
 24. The method of claim 21,wherein percutaneously inserting the guidewire further includesproviding a biopsy needle defining a lumen extending therethrough andincluding a stylet having a sharpened distal tip, the stylet being sizedto be removably positioned within the lumen and further includinginserting the biopsy needle into the boney structure such that thesharpened distal tip makes a puncture in the boney structure.
 25. Themethod of claim 24, wherein percutaneously inserting the guidewire intothe boney structure includes removing the stylet from the lumen of thebiopsy needle after the biopsy needle is inserted into the boneystructure and inserting the guidewire through the lumen of the biopsyneedle.
 26. The method of claim 21, further comprising dissecting tissueto expand an operating space.
 27. The method of claim 26, furthercomprising providing a cannulated scalpel and wherein dissecting tissueincludes cutting tissue with the cannulated scalpel along the guidewireto expand the operating space.
 28. The method of claim 21, furthercomprising dilating tissue around the guidewire.
 29. The method of claim21, further comprising drilling a threaded bore in the boney structurewith a cannulated bone drill or tap.
 30. The method of claim 21, furthercomprising inserting a rod through the retractor until the rod reachesthe cannulated bone screw.
 31. The method of claim 21, wherein severingthe portion of the retractor such that the proximal portion of theretractor remains flush with the external surface of the skin isperformed after spreading the retractor from the pivot point adjacentthe cannulated bone screw to retract soft tissue and provide access tothe target site.
 32. A method of performing surgery comprising:percutaneously inserting a guidewire through a patient's skin into aboney structure; inserting a cannulated bone screw and associatedretractor over the guidewire to a target site; implanting the cannulatedbone screw into the boney structure; spreading the retractor from apivot point adjacent the cannulated bone screw to retract soft tissue;severing a portion of the retractor such that a proximal portion of theretractor is flush with an external surface of the skin; furtherspreading the retractor to retract soft tissue and provide access to thetarget site; performing a surgical procedure at the target site throughthe retractor; and removing the retractor from the cannulated bonescrew.